How to Block Your Cell Phone Number When Calling Someone
Blocking your number before making a call is one of the most straightforward privacy tools built into every modern phone — yet many people don't know it exists or aren't sure which method works best for their situation. Here's a clear breakdown of how it works, what controls it, and why the same approach doesn't produce identical results for every caller.
What "Blocking Your Number" Actually Means
When you place a call, your phone transmits your number as part of the call setup process. This is known as Caller ID, and it's delivered to the recipient's phone automatically unless you actively suppress it.
Blocking your number tells the carrier's network to withhold that information before the call connects. The recipient's phone receives the call, but instead of seeing your number, they see "No Caller ID," "Private Number," or "Unknown" — depending on their device and carrier.
This works at the network level, not just the app level. The suppression request travels with the call signal itself.
The Two Main Ways to Block Your Number
1. Per-Call Blocking with a Prefix Code
The most universally supported method is dialing *67 before the number you're calling. This is available on virtually all U.S. cell phones and landlines, regardless of carrier or device.
How to use it:
- Dial:
*67 + the full number(e.g.,*67-555-867-5309) - Press call as normal
- Your number is withheld for that single call only
This method is temporary — it applies to one call at a time. Your next call goes out with your number visible again.
📞 Outside the U.S., the prefix code differs. Common alternatives include #31# (used in many European countries and on some international carriers). If you're calling internationally or using a foreign SIM, check your carrier's documentation for the correct prefix.
2. Permanent Caller ID Blocking Through Settings
Most carriers allow you to request permanent Caller ID suppression on your account. When enabled, every outgoing call automatically hides your number — no prefix required.
This setting is usually managed in one of three places:
- Your carrier's account portal or app
- A call to customer support
- Your phone's built-in settings (varies by device and OS)
On iPhone, navigate to: Settings → Phone → Show My Caller ID and toggle it off.
On Android, the path varies by manufacturer and carrier, but it's typically found under: Phone app → Settings → Calls → Additional Settings → Caller ID → select "Hide number."
Important caveat: Some carriers override this setting on certain networks, or the option may be grayed out depending on your plan or account type. Not every carrier exposes this control directly in the phone's UI.
Variables That Affect How This Works in Practice
Several factors determine exactly what happens when you block your number — and whether it works the way you expect.
| Variable | What It Affects |
|---|---|
| Carrier | Whether permanent suppression is available and how it's managed |
| Device OS / version | Whether the in-phone toggle exists and where it lives |
| Call type (cellular vs. VoIP) | VoIP apps handle Caller ID differently than native calls |
| Recipient's carrier | How "blocked" numbers are displayed on their end |
| International routing | *67 may not carry through international calls reliably |
VoIP and third-party calling apps — including some business phone apps, Google Voice, and similar services — have their own Caller ID settings that operate independently of your phone's native dialer. Blocking through *67 or your phone settings may not suppress the number displayed when using those apps.
When Blocking Doesn't Work as Expected 🔍
There are situations where your number may still appear despite blocking:
- Emergency services (911): Caller ID suppression is bypassed entirely for emergency calls. This is by law and by design.
- Toll-free numbers: Many businesses and 1-800 numbers use services that can reveal the calling number even when blocked, through a feature called ANI (Automatic Number Identification), which operates separately from Caller ID.
- Calls to certain VoIP numbers: Depending on routing, suppression may be stripped.
- Carrier-to-carrier inconsistencies: A suppressed number on one network doesn't always display as "No Caller ID" on another — it may show as "Unknown" or a generic placeholder.
The Spectrum of Use Cases
Someone making a one-off call to an unfamiliar number has very different needs from a professional who wants every outgoing call to appear private. A person using a VoIP-based work line operates in a completely different technical environment than someone on a standard prepaid SIM.
The per-call *67 method is the lowest-friction option — no setup, no account changes, works immediately. The permanent suppression setting suits people who want consistent privacy without remembering to dial a prefix every time. And for those using calling apps or business phone systems, the relevant setting usually lives inside that app's configuration — not the phone's native dialer.
Your carrier's specific policies, the version of Android or iOS you're running, and whether your calls go through a standard cellular network or a VoIP layer all shape which method works cleanly and which requires extra steps. Those details live in your own setup — and that's the part no general guide can fully account for.